Dichroism Signal Research Articles

A Carbazole‐Centered Expanded Helicene Stabilized with Hexabenzocoronene (HBC) Units

The synthesis and stabilization of heteroatom‐doped nanocarbon molecules, such as carbazole‐containing (super)helicenes, present significant challenges due to the complexities involved in maintaining structural integrity and electronic functionality. In this study, we successfully synthesized a carbazole‐centered expanded tris‐hexabenzo[7]helicene (1) via a facile FeCl3‐mediated Scholl coupling reaction. 1 exhibits both chemical and chiral stability and demonstrates fluorescence at 628 nm with a quantum yield of 0.40. Additionally, the enantiomers of 1 display pronounced chiroptical properties, including a distinct circular dichroism (CD) signal spanning from 300 to 600 nm. The absorption dissymmetry factor (|gabs|) is determined to be 2.98 × 10−3, while the circularly polarized luminescence brightness (BCPL) is measured as 32.50 M−1 cm−1.

Self-Assembly of Chiral Ligands on 2D Semiconductor Nanoplatelets for High Circular Dichroism.

Group II-VI semiconductor nanoplatelets (NPLs) with atomically defined thicknesses and extended atomically flat (001) facets are used for ligand binding and chiro-optical effects. In this study, we demonstrate that tartrate ligands, anchored by two carboxylate groups, chelate the (001) facets of NPLs at an average ratio of one tartrate molecule to two cadmium (Cd) surface atoms. This assembly of chiral molecules on inorganic nanocrystals generates a circular dichroism g-factor as high as 1.3 × 10-2 at the first excitonic transition wavelength of NPLs. Tartrate ligands induce an orthorhombic distortion of the initially "cubic" crystal structure, classifying the NPLs within the 222-point group. Unlike spherical nanocrystals, where it is difficult to discern whether chiral ligands affect only the surface atoms or the entire crystal structure, our findings unequivocally show that the crystal structure of NPLs is modified due to their thinness and atomically precise thickness. The in-plane lattice parameters experience compressive and tensile stresses, significantly splitting the heavy-hole and light-hole bands. Additionally, tartrate ligands adopt different conformations on the NPL surface over time, resulting in dynamic changes in the circular dichroism signal, including an inversion of its sign.

Engineering circularly polarized luminescence through symmetry manipulation in achiral tetraphenylpyrazine structures

Symmetry breaking, a critical phenomenon in both natural and artificial systems, is pivotal in constructing chiral structures from achiral building units. This study focuses on the achiral molecule 8,8',8'',8'''-((pyrazine-2,3,5,6-tetrayltetrakis(benzene-4,1-iyl))tetrakis(oxy))tetrakis (octan-1-ol) (TPP-C8OH), an aggregation-induced emission (AIE) molecule, to explore its symmetry breaking behavior in supramolecular assembly. By analyzing TPP-C8OH in various solvents‒both non-chiral and chiral‒ we found that chiral solvents significantly enhance the molecule’s symmetry breaking and chiroptical properties. Specially, alcohol solvents, particularly dodecyl alcohol, facilitated the formation of helical structures with both left-handed (M) and right-handed (P) helices within single twisted nanoribbons. This observation contrasts with previously reported symmetry breaking phenomena in assembly systems. Chiral solvents induced assemblies with distinct helical orientations, resulting in notable circularly polarized luminescence (CPL) and circular dichroism (CD) signals. This study elucidates the impact of solvent choice on symmetry breaking and chiral assembly, offering insights into the design of advanced chiral materials with tailored self-assembly processes.

Encasing Triaryltriazine with a Bulky Chiral Cap: Luminescent Chiral Crystalline Molecular Rotors with Modulation of Solid-State Chiroptical Properties Mediated by Molecular Rotation.

A novel structural motif for luminescent chiral crystalline molecular rotors with chiroptical properties correlated with the rotational motion in crystalline media is presented. This scaffold incorporates bulky chiral caps consisting of a homochiral binaphthyl moiety with a triisopropylsilyl (TIPS) group into triaryltriazine, as confirmed by single-crystal X-ray diffraction (XRD) analysis. Variable-temperature solid-state 2H NMR studies revealed a 4-fold rotation of the phenylenes occurred in the rotor crystal between 263 and 333 K, while a steric rotor analogue shows no rotational motion. Notably, a reduction in the dihedral angle of the binaphthyl moiety upon heating was observed in the chiral rotors, and a corresponding alteration of the circular dichroism (CD) signal was detected in the solid-state, while those of the steric rotors showed no alteration by the temperature change. We propose that the fast rotation of the phenyl rings affects the motion of neighboring isopropyl groups, leading to steric repulsion with the binaphthyl moieties and thereby inducing its conformational change. Furthermore, the chiral rotors exhibited circularly polarized phosphorescence in the solid-state at low temperature, originating from rotational displacement of the phenylene on triphenyltriazine during structural relaxation in the excited state. Meanwhile, the steric rotors showed significant circularly polarized fluorescence induced by the suppressed molecular motion via a sterically hindered lattice environment in the excited state. These results indicate that the bulky chiral cap introduced into the triaryltriazines, acting as a luminescent chiral crystalline molecular rotor, can be a useful scaffold for the modulation of solid-state chiroptical properties via molecular rotational motions.

Chiroptical Sensing of Amines With Isatins.

Isatins are extensively researched compounds with diverse applications, particularly as synthetic precursors in pharmaceutical developments. However, their use as optical probes for enantioselective sensing of chiral amines has not been explored to date. Herein, we present a novel chiroptical assay with an optimized isatin that generates strong, red-shifted circular dichroism (CD) signals at approximately 380 nm upon ketimine formation with chiral amines. The intensity of the induced CD signal increases linearly with the enantiomeric excess of the analyte and thus allows quantitative chirality analysis. The general usefulness of this approach is demonstrated with a broad range of aliphatic and aromatic chiral amines, and by accurate determination of the enantiomeric composition of 10 samples.

Deconvolution of X-ray natural and magnetic circular dichroism in chiral Dy-ferroborate.

Structural chirality and magnetism, when intertwined, can have profound implications on materials properties. Using X-ray imaging and spectroscopic measurements that leverage the natural and magnetic circular dichroic effects present in magnetized chiral crystal structures, we probe the interplay between chirality and magnetism across the field-induced spin-flop transition of Dy ferroborate, ( ) . Deconvolution of natural and magnetic circular dichroic signals at the Fe K and Dy L absorption edges of the non-centrosymmetric structure was enabled by use of tunable temperature and magnetic field, providing access to element-specific magnetic information across the spin-flop transition. The magnetic response of Fe and Dy sublattices was found to be independent of domain chirality. The chiral domains were robust against both the (chirality preserving) R32 to P3 21/P3 21 structural phase transition at 280 K, and application of magnetic field up to 4 Tesla. A third flavor of X-ray dichroism, magneto-chiral dichroism, was not detected within the accuracy of our measurements. The absence of significant Fe magnetization along the screw, c-axis for the magnetic field strength used in this study, together with non-linear coupling of magnetic field to electric polarization across the spin-flop transition, may hinder observation of magneto-chiral dichroic effects in this system.

Intense Circular Dichroism and Spin Selectivity in AgBiS2 Nanocrystals by Chiral Ligand Exchange.

Chiral semiconducting nanomaterials offer many potential applications in photodetection, light emission, quantum information, and so on. However, it is difficult to achieve a strong circular dichroism (CD) signal in semiconducting nanocrystals (NCs) due to the complexity of chiral ligand surface engineering and multiple, uncertain mechanisms of chiroptical behavior. Here, a chiral ligand exchange strategy with cysteine on the ternary metal chalcogenide AgBiS2 NCs is developed, and a strong, long-lasting CD signal in the near-UV region is achieved. By carefully optimizing the ligand concentration, the CD peaks are observed at 260 and 320nm, respectively, giving insight into the different ligand binding mechanisms influencing the CD signal of AgBiS2 NCs. Using density-functional theory, a large degree of crystal distortion by the bidentate mode of ligand chelation, and efficient ligand-NC electron transfer, synergistically resulting in the strongest CD signal (g-factor over 10-2) observed in chiral ligand-exchanged semiconductor NCs to date, is demonstrated. To demonstrate the effective chiral properties of these AgBiS2 NCs, a spin-filter device with over 86% efficiency is fabricated. This work represents a considerable leap in the field of chiral semiconductor NCs and points toward their future applications.

Perylene-Embedded Helical Nanographenes with Emission up to 1010 nm: Synthesis, Structures, and Chiroptical Properties.

Near-infrared (NIR) circularly polarized absorbing or emitting materials offer distinct advantages over their visible-light counterparts and have attracted considerable interest across various fields. Materials exhibiting NIR chiroptical properties with high fluorescence quantum yields (ΦF) are particularly rare. In this study, we report the synthesis of a series of helical nanographenes (1, 2, 3, and 4), where perylene is fused with one to four hexa-peri-hexabenzocoronene (sub)units via a strategy involving Diels-Alder cycloaddition followed by Scholl reaction. X-ray crystallographic analysis confirmed their structures, revealing helicene moieties integrated into a highly contorted framework. Benefiting from a similar distribution pattern of frontier molecular orbitals to perylene and extended π-conjugation, compounds 1-4 demonstrate respectable ΦF values of 31.9%, 15.0%, 13.7%, and 6.5%, respectively, with emission maxima reaching up to 1010 nm. Their enantiopure forms, isolated by preparative chiral HPLC, exhibit distinct circular dichroism signals and circularly polarized luminescence across a broad spectral range, extending from the ultraviolet to the NIR.

Circularly Polarized Light-Induced Chiral Growth of Achiral Plasmonic Nanoparticles Dispersed in a Solution.

Plasmonic nanoparticles (NPs) with chiral geometries have wide applications from chiral molecular sensing to enantioselective catalysis. The synthesis of chiral plasmonic nanoparticles using circularly polarized light (CPL) has attracted a considerable amount of attention because it eliminates the need for chiral molecules. However, NPs need to be immobilized on a solid substrate during synthesis. Here, we successfully synthesized colloidal chiral plasmonic NPs by depositing silver on the surface of achiral gold nanoparticles dispersed in a solution using CPL. Circular dichroism (CD) signals corresponding to the handedness of the irradiated CPL were observed when gold nanorods or gold nanotriangles were used. In contrast, no clear CD signal was observed when gold nanospheres were used. The morphological anisotropy of the gold nanoparticles was a key factor in the synthesis of chiral plasmonic nanoparticles using CPL. Furthermore, we demonstrated the tuning of chiroptical properties according to the CPL wavelength.

A pH visual sensing platform based on dual-emission chiral carbon dots for discrimination of normal/cancer cells and monitoring food freshness

Accurate detection of pH is important in pathological processes and food freshness. Developing sensors of sensitive response and visualization for pH is highly demanded. In this work, Chiral carbon dots(CCDs) was synthesized via one-pot hydrothermal process using o-phenylenediamine and L-Tryptophan, which displayed circular dichroism (CD) signals at 200–255 nm and 255–300 nm. The CCDs exhibited dual-emission peaks with blue and red emission bands when excited at 360 nm. The ratiometric signals of UV–vis absorption and fluorescence intensity of L-CDs were responsive over the pH range of 2.0 to 11.0 with significant color changes in solution. Fluorescence imaging of live cells displayed different signals related to pH in both the blue and red channels, allowing accurate measurement of the pH of the cellular environment. Furthermore, the pH test paper based on L-CDs enabled monitoring the freshness of shrimp and pork under 365 nm UV light. Therefore, L-CDs provided a multifunctional visual pH sensing platform for environmental monitoring and biosensing.

A Method of Laser Frequency Stabilization Based on the Effect of Linear Dichroism in Alkali Metal Vapors in a Modulated Transverse Magnetic Field

We present a method of laser frequency stabilization based on the linear dichroism signal in a transverse magnetic field. This method is similar to the DAVLL (Dichroic Atomic Vapor Laser Lock) method. It differs from DAVLL and from its existing modifications primarily by the fact that it uses signals of linearly polarized light caused by alignment, rather than circular refraction caused by orientation, and therefore allows us to obtain error signals at the magnetic field modulation frequency (or its second harmonic) by extremely simple means. The method allows the laser frequency to be stabilized in the vicinity of the low-frequency transition in the D1 line of Cs; it does not require strong magnetic fields or careful shielding of cells containing cesium atoms. Although the absorption line in a gas-filled cell is typically gigahertz wide, the achievable resolution, limited by the signal-to-noise ratio of photon shot noise, can reach units or tens of kilohertz in a one hertz bandwidth.

Configurationally Stepping Confinement Achieved Tunable Chiral Near-Infrared Luminescence Supramolecular Phenothiazine Organic Framework.

Herein, thermally responsive reversible chiral supramolecules are reported, constructed by the chirality transfer from tripeptides to achiral network supramolecular organic frameworks (SOF) based on configurationally stepping confinement, which displayed not only highly selective reversible chirality transfer but also efficient enhanced near-infrared (NIR) luminescence. Taking advantage of macrocyclic confinement, CB[8] separately encapsulated two kinds of tetracationic bis(phenothiazines) derivatives (G1, G2) at 2:1 stoichiometric to form organic 2D SOFs, efficiently enhancing 12.6 fold NIR luminescence and blueshifted from 705 to 680 nm for G1, and redshifted from 695 to 710 nm for G2, respectively. Uncommonly, the tripeptide coassembled with two kinds of achiral noncovalent frameworks (G1/CB[8] or G2/CB[8]) displayed different opposite circular dichroism signals based on different binding modes and affinity, achieving chirality transfer from tripeptide to organic supramolecular assemblies with further enhanced NIR fluorescence up to 46.2 times and the quantum yield (QY) increased from 0.71% to 10.29% for G2/CB[8], showing reversible chirality transfer and tunable NIR fluorescence under thermal stimulus. Therefore, the current research has achieved controllable chirality transfer from tripeptide to the SOFs and the enhancement of tunable NIR fluorescence, which is successfully applied in thermal responsive chiral logic gates, information encryption, and cell imaging.

The Phenomenon of Vibrational Circular Dichroism Enhancement: A Systematic Survey of Literature Data.

While the intensity of vibrational circular dichroism (VCD) signals is commonly 104-105 times smaller than that of corresponding IR signals, several kinds of systems display enhanced VCD spectra with g-values (VCD/IR intensity ratio) above 10-3 and even reaching 5 × 10-2 in some exceptional cases. These systems include transition metal and lanthanide complexes, protein and peptide fibrils, short oligopeptide gels, crystalline compounds, gels and solution aggregates of organic compounds. We review the literature on VCD enhancement, focusing on collecting and analyzing data on enhanced g-values. Special attention is given to the mechanisms proposed to produce these effects.

W-Shaped π-Extended Double Undecabenzo[7]helicene.

A chiral W-shaped fully π-extended double [7]helicene (ED7H) has been synthesized and fully characterized. It displays fluorescence emission (λem = 636 nm) with a quantum yield (Φf) of 0.10. In comparison to its X-shaped and monomict π-extended [7]helicene analogues, enantiopure W-shaped ED7H exhibited superior chiral optical characteristics, including distinct circular dichroism signals from 400 to 650 nm, a good dissymmetric emission factor |glum| of 4 × 10-3, and a circularly polarized luminescence brightness value BCPL of 42 M-1 cm-1.

Magnetic symmetries of terbium tetraboride (TbB4) revealed by resonant x-ray Bragg diffraction

A recent experimental study of TbB4 at a low temperature using resonant x-ray Bragg diffraction implies a magnetic symmetry not found in any other rare-earth tetraboride. The evidence for this assertion is a change in the intensity of a TbB4 Bragg spot on reversing the handedness (chirality) of the primary x-ray beam [R. Misawa, K. Arakawa, T. Yoshioka, H. Ueda, F. Iga, K. Tamasaku, Y. Tanaka, and T. Kimura, ]. It reveals a magnetic chiral signature in TbB4 that is forbidden in phases of rare-earth tetraborides known to date, as the previous magnetic symmetries are parity-time (PT) symmetric with anti-inversion present in the magnetic crystal class. Misawa appeal to a PT-symmetric diffraction pattern to interpret their interesting diffraction patterns. In addition to the use of symmetry that does not permit a chiral signature, calculated patterns impose cylindrical symmetry on Tb sites with no justification. We review magnetic symmetries for TbB4 consistent with a published neutron powder diffraction pattern and susceptibility measurements. On the basis of this information, noncollinear antiferromagnetic order exists below a temperature ≈44 K with no ferromagnetic component. Our symmetry-informed patterns encapsulate Tb electronic degrees of freedom in terms of multipoles consistent with established sum rules for dichroic signals. The investigated symmetry templates are noncentrosymmetric, noncollinear antiferromagnetic constructions with propagation vector k=(0,0,0). An inferred chiral signature for a parity-even absorption event has an interesting composition. There is the anticipated product of Tb axial dipoles and chargelike quadrupoles (from Templeton-Templeton scattering). Beyond this contribution, though, symmetry allows a product of dipoles in the chiral signature. A predicted change in the intensity of a Bragg spot with rotation of the crystal about the reflection vector (an azimuthal angle scan) can be tested in future experiments. Likewise contributions to Bragg diffraction patterns from Tb anapoles and higher-order Dirac multipoles. Published by the American Physical Society 2024

Optically Ambidextrous Reflection Circularly Polarized Luminescence Film with High Dissymmetry Factor and On‐Demand Handedness

AbstractThe self‐assembled cellulose nanocrystal (CNC) film has a left‐handed layered structure, which makes the reflection of right‐handed circularly polarized (CP) light a challenge. Herein, a nematic phase layer is designed and inserted into the chiral organization, to work as a half‐wave retarder and make the ambidextrous CP light reflection. The maximum reflectivity exceeds 80%, which breaks the 50% limitations of single‐direction light reflection and is the current maximum in all the reported CNC‐based films. This “sandwich‐like” structure displays different optical properties on both sides, displayed as the chromatism and the inversion of the circular dichroism signals. The dual CP light reflection and direction‐dependent optical phenomena are reserved in the synthesized circularly polarized luminescence (CPL) film, with the dissymmetry factor (glum) of −0.4245. However, this luminescent intensity and single‐direction emission are not enough in advanced optical systems. This work designs a triple CPL amplification path and develops the handedness inversion strategy, with the glum of −1.0551 and 0.4082. Then, the dual‐directional CPL emission films are designed, where the chiral optics can be switched on‐demand. Finally, the photonic crystal films are applied in the anti‐counterfeit and chiral superstructure induction.

Self‐Standing Chiral Covalent Organic Framework Thin Films with Full‐Color Tunable Guest‐Induced Circularly Polarized Luminescence

Exploring self‐standing chiral covalent organic framework (CCOF) thin films with controllable circularly polarized luminescence (CPL) is of paramount significance but remains challenging. Herein, we demonstrate the first example of self‐standing CCOF films employing a polymerization‐dispersion‐filtration strategy. Pristine, low‐quality CCOF films were produced by interfacial polymerization and then re‐dispersed into COF colloidal solutions. Via vacuum assisted assembly, these COF colloids were densely stacked and assembled into self‐standing, pure chiral COF films (L‐/D‐CCOF‐F) that were transparent, smooth, crack‐free and highly crystalline. These films were tunable in thicknesses, areas, and roughness, along with strong diffuse reflectance circular dichroism (DRCD) and cyan CPL signals, showing an intrinsic luminescence asymmetric factor (glum) of 4.3×10‐3. Furthermore, these COF films served as host adsorbents to load various achiral organic dye guests through adsorption. The effective chiral transfer and energy transfer between CCOF‐F and achiral fluorescent dyes endowed the dyes with strong chirality and tunable DRCD, resulting in intense, full‐color‐tunable solid‐state CPL. Notably, the ordered arrangement of dye guest molecules within the preferentially oriented chiral pores of CCOF‐F contributed to an amplified |glum| factor of 7.2×10‐2, which is state‐of‐the‐art for COF‐based CPL materials. This work provides new insights into the design and fabrication of self‐standing chiral COF films.

Rational Design of Multi‐color Phosphorescent Carbon Dots Based on Binaphthyldiamine with Chiral Signals

Comprehensive SummaryChiral phosphorescent materials have received extensive research owing to the unique properties of optical activity in recent years. Many phosphorescent carbon dots (CDs) materials have been reported, but the research on chiral phosphorescence is still in the exploratory stage. This work designs multi‐color room temperature phosphorescent (RTP) CDs with chiral signals, which are fully mixed with aromatic aldehyde precursors and chiral amino compounds precursors in a boric acid (BA) matrix and can be easily prepared by solvent‐free thermal method. The prepared (R)‐GCDs, (R)‐YCDs and (R)‐RCDs achieved phosphorescence emission at 545 nm, 582 nm, and 654 nm, respectively, and exhibited corresponding circular dichroism (CD) signals at 341 nm, 394 nm, 384 nm, and 380 nm, 448 nm, and 435 nm, respectively. The longest phosphorescence lifetime is up to 946 ms. Specifically, YCDs exhibit time‐dependent phosphorescence under UV excitation, and the afterglow time under white light excitation can reach 40 s. This article provides a new approach to the study of chiral phosphorescence.

Soft X-Ray Phase Nanomicroscopy of Micrometer-Thick Magnets

Imaging of nanoscale magnetic textures within extended material systems is of critical importance to both fundamental research and technological applications. While high-resolution magnetic imaging of thin nanoscale samples is well established with electron and soft x-ray microscopy, the extension to micrometer-thick systems currently requires hard x rays, which limits high-resolution imaging to rare-earth magnets. Here, we overcome this limitation by establishing soft x-ray magnetic imaging of micrometer-thick systems using the pre-edge phase x-ray magnetic circular dichroism signal, thus making possible the study of a wide range of magnetic materials. By performing dichroic spectroptychography, we demonstrate high spatial resolution imaging of magnetic samples up to 1.7 μm thick, an order of magnitude higher than conventionally possible with soft x-ray absorption-based techniques. We demonstrate the applicability of the technique by harnessing the pre-edge phase to image thick chiral helimagnets, and naturally occurring magnetite particles, gaining insight into their three-dimensional magnetic configuration. This new regime of magnetic imaging makes possible the study of extended non-rare-earth systems that have until now been inaccessible, including magnetic textures for future spintronic applications, non-rare-earth permanent magnets for energy harvesting, and the magnetic configuration of giant magnetofossils. Published by the American Physical Society 2024

(Invited) Near Field Photocatalysis for Site-Selective Reactions By Using ZnO Nanoplates

Nanofabrication is a technology for control of the morphology, orientation, and configuration of nanomaterials. When ordinary, propagating light is employed as a processing tool, subwavelength fabrication is difficult due to the diffraction limit. However, if optical near field, which is localized in a subwavelength region is used, nanofabrication beyond the diffraction limit is possible.We have demonstrated that subwavelength nanofabrication is possible by taking advantage of the optical near field. Since hot electron-hole pairs are generated at around the plasmonic resonance sites, the energetic carriers can be used to drive oxidative dissolution of Ag,1,2 oxidative deposition of PbO2,3,4 and reductive deposition of Ag,5 in a site-selective manner. These techniques have been applied to subwavelength photochromic data storage,1,2 fabrication of chiral nanoparticles,4-7 and site-selective modification of a plasmonic photocatalyst with a co-catalyst.8 Generation of optical near field is possible even at non-plasmonic, semiconducting or dielectric nanostructures. Here we employed In-doped ZnO (In:ZnO) as a semiconductor photocatalyst. Hexagonal In:ZnO nanoplates were synthesized and adsorbed onto a glass substrate, and irradiated with linearly polarized UV light in the presence of Ag ions for reductive deposition of Ag. The optical near field generated under polarized UV light gave rise to site-selective Ag deposition. Also, the sample exhibited linear dichroism (LD) signals, indicating that the nanoparticles have optical anisotropy. On the other hand, unpolarized UV light gave no optical anisotropy. Electromagnetic simulations successfully reproduced the LD spectra. We have also performed site-selective oxidation reactions by using the hexagonal In:ZnO nanoplates. Tanabe, I.; Tatsuma, T. Nano Lett. 2012, 12, 5418–5421. Saito, K.; Tanabe, I.; Tatsuma, T. J. Phys. Chem. Lett. 2016, 7, 4363–4368.Nishi, H.; Sakamoto, M.; Tatsuma, T. Chem. Commun. 2018, 54, 11741–11744.Saito, K.; Tatsuma, T. Nano Lett. 2018, 18, 3209–3212.Ishida, T.; Isawa, A.; Kuroki, S.; Kameoka, Y.; Tatsuma, T. Appl. Phys. Lett. 2023, 123, 061111.Morisawa, K.; Ishida, T.; Tatsuma, T. ACS Nano 2020, 14, 3603–3609.Shimomura, K.; Nakane, Y.; Ishida, T.; Tatsuma, T. Appl. Phys. Lett. 2023, 122, 151109.Kim, K.; Nishi, H.; Tatsuma, T. J. Chem. Phys. 2022, 157, 111101.